My earlier patent, U.S. Pat. No. 6,435,026, the disclosure of which is incorporated by reference herein, describes a magnetically operated liquid level indicator of the kind having a magnetized float which moves as the level of liquid changes in the tank. The position of the float is remotely sensed by a plurality of magnetized indicator elements disposed one above the other and past which the magnetized float travels in a standpipe tubing as the liquid level rises or falls. The indicator elements partly rotate under the influence through the tubing wall of the magnetized float to provide a visual indication of the liquid level contained in the vessel.
One of the shortcomings of prior art level indicators of this type is that it is difficult to read them during hours of darkness, particularly from a distance. An illuminated device would be desirable.
Another of the shortcomings of prior art level indicators of this type is lack of remote reading capabilities. An add-on device having the capabilities of sending electronic level signals to a remote location for reading there would be desirable. Stand-alone capabilities for the device would be further desirable.
Another shortcoming of prior art indicators is a practical upper limit to operating temperature. Where the indicator is used to measure the liquid level of hot fluids, exposure to excessively hot temperatures can lead to failures. An indicator which has good high-temperature resistance would be very desirable.